Along with the development of communication techniques represented by the Internet, delivery of news articles on a network and e-mail have prevailed. Since it is desirable to quickly offer such information to the user, terminal devices such as a personal computer, portable phone, and the like, which can inform the user of incoming information, have been proposed. Also, a terminal device which not only displays such information on a display but also outputs it by synthesizing speech has also been proposed.
The speech output requires user's attention less than display on the display. Hence, the user can hear the output speech to confirm the contents of information while he or she does something else.
However, the speech output using such synthetic speech poses a problem when the user is listening to another audio such as music or the like by the terminal device. For example, when the contents of a received e-mail message are read using synthetic speech which is superposed on a piece of music while the user is listening to the music, the user may hardly catch the synthetic speech. On the other hand, if the contents of the received e-mail message are suddenly read while the user is listening to the music, such operation may suddenly spoil user's pleasure.